Tablets and evaporation devices using these type of tablets are described for instance in the patent publications WO 97/45008 and EP-0.498.278. Typically, these tablets are a flat body and are arranged parallel to the heating means of an electric evaporation device.
It is known that this type of tablets provide a “a first step of high evaporation rate” effect the first time there are used, so that a great amount of volatile substance is evaporated and dispersed to the ambient in a short time, the first time that the tablet is used in an electric evaporation device. Subsequently, after said first step of high evaporation rate, the amount of volatile substance diffused to the ambient is reduced significantly and progressively until its complete evaporation.